Like a teenager examining a typewriter or an eight-track tape, Rams middle linebacker James Laurinaitis scratched his head this past week while studying video of the 49ers' offense.

In today's I-formation era, the 49ers will split running backs Frank Gore and Kendall Hunter at equal depth in the backfield, the NFL equivalent of using a rotary phone. From that formation, they will run double sweeps and two-back traps - X's and O's straight out of a '90s video game.

"They run some weird running plays now," Laurinaitis said. "You'll see some running plays I don't think I've seen since Tecmo Super Bowl."

In a league where pass-driven, spread offenses are presumed to be the future, the 49ers are turning back the clock by emphasizing that relic known as the running game.

Nearing NFL record

Entering Sunday's game against visiting St. Louis, the 49ers, one of four teams with more rushing attempts than passes this season, lead the NFL in rushing (168.6 yards per game), and their 5.64 yards per attempt is threatening the league record of 5.74 held by the 1963 Browns.

That Cleveland team was headlined by Jim Brown, perhaps the greatest running back in league history, who led the Browns to the NFL championship the following year.

If the 49ers realize their own championship aspirations this season, they will buck a trend in a pass-driven league: A team hasn't won a Super Bowl without a 1,000-yard receiver since the 2005 Steelers, and the last champion with a 1,000-yard rusher was the 2007 Giants. Midway through the season, San Francisco's leading wide receiver, Michael Crabtree, is on pace for 880 yards while Gore is on pace for 1,312 yards, which would be his highest total since 2006.

At 29, an age when elite NFL running backs often are shoved into supporting roles, Gore also is averaging a career-best 5.5 yards a carry, 1.2 more than his average from 2010-11. Gore said he's had plenty of help in finding the fountain of youth.

"My o-line's been doing a hell of a job springing me and giving me big lanes that I've never seen before," Gore said. "Coach G-Ro's doing a great job scheming."

Roman served as an offensive assistant with the Panthers from 1999 to 2001 under former 49ers coach George Seifert, who brought Walsh's offense to Carolina. Since arriving in San Francisco last year, Roman has also pored over Walsh's dusty offensive installation tapes.

"The person that really taught me all that was George Seifert ...," Roman said. "He had a tremendous impact on me as a football coach. I was privy to all that stuff back then, and got to watch all the films."

Those influences can be seen in the split-back formation, which the 49ers used a quarter-century ago with running back Roger Craig and fullback Tom Rathman. Roman has also taken advantage of his offensive line's athleticism to implement blocking schemes similar to those of legendary 49ers line coach Bobb McKittrick. A prime example is an old-fashioned power sweep in which guards Mike Iupati and Alex Boone both pull to form the outside wall.

Center Jonathan Goodwin, an 11-year veteran who spent his first nine seasons with the Jets and Saints, was in for an education when he signed with the 49ers in 2011.

Trap-happy

"There are definitely some new things and some old-school things that we're doing," Goodwin said. "It's not similar to what I've done in other places. Some of the backfield sets, some of the plays, are things that haven't been seen too much in the NFL recently. Some teams have run traps, but I'm not sure they've done it as much as us."

In addition to their array of traps, the 49ers also mix in a blend of dives, powers and gimmick runs. Those gimmicks can put a new spin on an old play. The 49ers have unveiled a sweep, for example, in which both guards pull, but the running back flips a U-turn in the backfield and takes a pitch while running in the opposite direction of the linemen. It's all part of a playbook that Fox analyst and former NFL defensive lineman Tim Ryan conservatively estimates includes 15 runs, about triple the number of a typical team, he says.

Diversified run game

"Most teams around the NFL, even though they are mixing both zone and power (blocking schemes), have five or six runs," Ryan said. "I study them all. I chart their runs. It's a couple runs to the strong side. A couple runs to weak side. That's it. ... They don't really count on the run game as a weapon, as much as a methodical approach. ... The 49ers have ... by far, the most diversified run game in the NFL."

The volume of run plays presents a challenge for opponents, particularly those facing the 49ers on a short week. Last month, the Seahawks had just three days of advance work before a 13-6 Thursday night loss to San Francisco. Seattle, which entered allowing 70 rushing yards a game, surrendered 175 and was flummoxed by a series of second-half trap plays.

Rams coach Jeff Fisher, in his 33rd season as an NFL player or coach, no doubt feels fortunate to face the 49ers after coming off a bye.

"I can't remember having to prepare for an offense that was so well-coached and so diversified in the run game and so talented," Fisher said.

And so big.

Jumbo packages

While spread offenses are routinely bringing extra wide receivers onto the field, the 49ers often trot out additional linemen. On Gore's 23-yard touchdown run in a season-opening win at Green Bay, he ran over the right side of a seven-linemen formation that featured 355-pound guard Leonard Davis at tight end and 308-pound center Daniel Kilgore at wing back.

Such jumbo packages can be particularly effective against modern-day defenses, which have shrunk to combat the spread. There has been an influx of smaller and quicker ends and outside linebackers to keep up with the bevy of skill-position players in pass-happy attacks.

St. Louis' defensive ends, Chris Long and Robert Quinn, offer a prime example. Long and Quinn average 267 pounds, 4 pounds lighter than the average weight of Merlin Olsen and Deacon Jones, the Rams' Hall-of-Fame defensive ends who starred 40 years ago.

"The beauty of it all is it's old-school football in a modern era game," Ryan said. "Look at all of these defensive ends that are undersized. Everyone is running the spread with five- and six-man protections and you have to have the small, fast guys that can play against the no-huddle. So what do the Niners do? They come out and give you that big personnel grouping, and they're so big and physical up front. They're just going to pound on you."

Craig, the second-leading rusher in 49ers history, sees elements of Walsh's offense in San Francisco's run game, but believes the 49ers' physicality distinguishes it from the "finesse-type system" in which he played. For his part, Laurinaitis believes the offensive line's blend of strength and speed is what allows the 49ers to do it all on the ground.

The mauling option

"It's good stuff, and they have the personnel to do it because their offensive line can pull and get out there," Laurinaitis said. "Or if they want to, they can just come up and maul you."

Laurinaitis even spoke admiringly of a "triple trap" the 49ers run. A triple trap? Goodwin laughed when asked about the play.

"Yeah, I know what he's talking about," Goodwin said. "I would just say it's a play where a couple guys get blocked by guys they would least be expecting to block them."

Careful not to reveal any trade secrets, Goodwin didn't divulge more.

The full answer, however, could possibly be found in a certain '90s video game.

Rams at 49ers

1:25 p.m., Channel: 2 Channel: 40 680, 107.7

Spotlight on: CB Carlos Rogers. Rogers will match up in the slot against Rams wide receiver Danny Amendola, who is listed as questionable but is expected to play after missing three games with a shoulder injury. In the season's first four games, Amendola had 31 catches for 351 yards and tied an NFL record with 12 catches in the first half of a Week 2 win against Washington. Despite being sidelined, Amendola still leads St. Louis in receptions and yards. The Rams went 0-3 with Amendola out of the lineup.

Injury notes: 49ers - The 49ers listed nine players as probable on the injury report. Every member of the 53-man roster will be available. Rams - Starting left tackle Rodger Saffold (shoulder), who has missed the past six games, is questionable. Joe Barksdale will make his third career start if Saffold can't play.

Big 3

-- The 49ers have an 11-game home winning streak against NFC West opponents, the longest active streak in the NFL. Their last divisional loss at Candlestick was a 34-13 defeat to Seattle on Oct. 26, 2008.

-- Among running backs with a minimum of 60 carries, eight are averaging at least 5 yards per attempt. Three of those backs will play in Sunday's game: the 49ers' Frank Gore (5.5) and Kendall Hunter (5.0) and Rams' rookie Daryl Richardson (5.4).

-- Rams CB Cortland Finnegan has three interceptions and hasn't allowed a touchdown this season. Quarterbacks have a 64.8 rating when targeting Finnegan, according to Pro Football Focus.